In ectotherms, temperature is important as an environmental cue and as a rate-limiting factor in controlling all aspects of reptilian life processes. The parietal eye and pineal body (E-2 epiphyseal system) participate in the control and selection of optimal environmental temperatures and, thus, secondarily affect reptilian physiology and behavior. This project examines the functional relationship between the pineal, body temperatures which permit the expression of species-typical behavior, physiological apsects of reproduction, and the presence of the pineal hormone melatonin. Our finding of melatonin in alligators suggests that the production of melatonin is not limited to the pineal gland since alligators naturally lack pineal bodies.